This invention relates to chemical modification of unsaturated polyesters with poly[(alkionylimino)alkylene]s, otherwise known as poly(oxazolines).
Unsaturated polyesters are generally macromolecules with polyester backbones derived from the reaction of unsaturated diacids or unsaturated anhydrides with polyhydric alchols. The reaction normally proceeds at 190.degree.-220.degree. C. until a predetermined acid value/viscosity relationship has been achieved. Solutions of these polymers in vinyl monomers (e.g., styrene) are often called polyester resins. These are frequently compounded with filler or fibers and are cured with the aid of a free radical initiator. Unsaturated polyesters can be mass-cast, laminated, molded, pultruded, and made into gel coats in a variety of colors.
The physical properties of a cured polyester resin are interrelated to a certain degree with the structural features of the three-dimensional network. However, there is no unifying concept that correlates these features with the physical properties. The structure, ratio of acid and glycol components, molecular weight, polydispersity, type of end groups, and type of unsaturation can have varying effects upon the physical properties of the cured resin.
In spite of the lack of predictability inherent in this field, great strides have been made in producing high-quality unsaturated polyesters. However, the market place yearns for even further improvement in the physical properties of the cured resins. Specifically, improvements in properties such as hardness, heat distortion temperature, resistance to thermal aging, tensile strength, and flexural strength are desired.